A number of swimming strokes have evolved through the years by which humans are able to swim at or near the surface of the water and below the surface as well. Common surface swimming strokes include the crawl stroke as well as the breast stroke, back stroke and side stroke. Underwater swimming generally utilizes a stroke similar to the breast stroke. In addition, surfers propelling their surfboards through the water typically assume a kneeling position on the surfboard and propel themselves forward by bending forward and extending their arms on either side of the surfboard into the water and drawing themselves forward. While the particular characteristics of these strokes may vary, a common factor exists in that both swimmers and surfers use repeated motion in which one or both of the arms are extended forward in a reaching motion into the water at a point ahead of the swimmer or surfer's body followed by a drawing or pulling motion known as the power stroke. During the power, the hands and forearm are pulled back against the resistance of the water and until the arms are extended backwardly. At the conclusion of the power stroke, the return stroke is commenced and the arms are moved out of the water, usually raised being moved through the air above the water, and reached forward and back into the water to start the next power stroke.
As a result, despite the differences between the types of strokes employed and their timing and the details of stroke motion which are, to a large extent, varied as a matter of swimmer's style and selected stroke, virtually all swimming strokes, as well as the above-described surfer's paddling motion, may be increased in effectiveness by increasing the resistance to the movement of the arm through the water during the power stroke. This increased resistance permits the swimmer to impart greater energy to the water. Conversely, the desire is the opposite in the return stroke, namely to move the arm through the air and to the extent necessary, through the water with a minimum of resistance and lost energy.
Through various techniques, swimmers and surfers have employed certain changes during power and return strokes whereby he configurations and positions of the hands are used to provide a measure of this variable resistance to arm motion through the water. This duality of arm motion resistance is critical to the efficiency of the swimmer during the swimming process as well as the surfer during the paddling process. In essence, the difference between the force that a swimmer or surfer can generate in a forward direction during the power stroke and the resistance resulting from the swimmer's drawing the arm back from the end of a power stroke and repositioning it to commence another power stroke is the limit on a swimmer's efficiency.
In order to further enhance the capabilities of swimmers and surfers to stroking efficiency, there have been designed and created various swimming aid devices which generally comprise some type of fin or pair of fins attached to the swimmer's forearm. As will be seen in the discussion below, it is common to all such devices that a dual character is required in the power stroke and the return stroke. Typically, this duality is accommodated in some manner by which the surface area or contour of the device is altered in response to arm motion through the water.
The common factor in such swimming aids may be further generalized in that there is the provision of a greater effective surface area during the power stroke than during the return stroke.
One of the simpliest forms of swimming aids uses a substantially planar paddle-like structure attached to the hand and forearm of the swimmer which relies upon the swimmer's hand and wrist action to change the pitch of the paddle in the same fashion that a swimmer changes the pitch of his or her hand during normal swimming strokes. Such paddle devices however, have proved to be substantially inefficient and this inefficiency has caused practitioners in the art to create other swimming aids for use on a swimmer's forearm. Most such devices use pairs of fins which are pivotally arranged on the swimmer's arm and attached in such a manner that the swimmer's stroke motion causes the fins to move outwardly from the swimmer's forearm to increase effective area during the power stroke, and to move inwardly to a more collapsed position against the swimmer's forearm during the return stroke.
For example, U.S. Pat. No. 3,290,707 for a Swimming Aid filed in the name of Maxson H. Montgomery, sets forth a swimming aid in which a pair of plates are arranged side by side and attached to a resiliant band encircling the swimmer's arm such that the top of the band is disposed on the front side of the swimmer's arm. Resiliant attachment means secure the plates to the band and through their resiliance bias the plates toward a collapsed position against the swimmer's arm. During the power stroke, the resiliance of the attachment means is overcome by the force of the water against the underside of the plates causing them to pivot outwardly. During the return stroke, the opposite effect takes place in that the withdrawing motion of the return stroke causes the water flow over the top of the plates which together with the resiliant bias of the attachment means returns the plates to a collapsed position.
Another example is found in U.S. Pat. No. 3,827,095 for a Swim Fin filed by Alec Feather which sets forth a swim fin having a support strap attachable to the forearm of a swimmer in which the lower portion of the strap encircles the swimmer's forearm. A pair of laterally spaced fin members depend from the lower portion of the strap and extend outwardly from each other. As in the case of the above-described U.S. Pat. No. 3,290,707, the structure in U.S. Pat. No. 3,827,095 provides for motion of the forearm swim fins outwardly during the power stroke and inwardly during the return stroke. In addition, the device in U.S. Pat. No. 3,827,095 provides resiliant restraining means which are attached to the fin members so as to provide restraint of outward fin motion proportional to the force applied thereby producing resistance to the water during the power stroke in proportion to the applied force by the swimmer. The thrust of U.S. Pat. No. 3,827,095 is to provide fin members having positions adjusted automatically in response to variations in the force applied by the swimmer thereby accommodating the individual swimmer's strength. Still another example is found in U.S. Pat. No. 3,107,371 issued to Thomas E. Thompson which sets forth a swimming device having a generally tubular cuff-like member configured to be worn upon the forearm of the swimmer. A generally planar member is attached to the underside portion of the tubular member and extends outwardly therefrom and terminates in a pair of opposed fin members. The fin members are pivotally attached near the underside of the tubular member such that they are moveable between outwardly extended positions for the power stroke and downwardly extending positions during the return stroke. The function of the device set forth in U.S. Pat. No. 3,107,371 is directed to fulfilling substantially the same purpose as the above-described devices with the difference that the fin members are supported on the underside of the swimmer's forearm rather than on the upper surface. By way of further difference, provision is made in the device in U.S. Pat. No. 3,107,371 whereby the pivotal fin members assume different positions during the return stroke depending upon whether the return stroke is passing through the water or through the air. U.S. Pat. No. 3,097,375 issued to John D. Griffith, sets forth a forearm supported swimming aid having a pair of pivotally supported fins attached to the top portion above the outer surface of the swimmer's forearm. The device in U.S. Pat. No. 3,097,375 is similar in function to the above-described devices and further includes an additional support sling which encircles the little finger and thumb of the swimmer and is attached to the forearm support. The purpose of the hand sling is to inhibit rotation of the fin device during swimming strokes.
While the foregoing devices provide some improvement in the energy that a swimmer may apply to the water during the power stroke and do adjust to reconfigure during the return stroke, the prior art devices thus far have been subject to several limitations. In the devices provided thus far, the fins are not readily changed to accommodate different swimming conditions, different swimmers or different strokes. In addition, the hinge mechanisms utilized in the devices provided in the art thus far are somewhat imprecise and inconsistant in their control of the fin attitudes during the swimming strokes. Further, the prior art devices have not provided a swimming aid which includes the capability to precisely control the change in fin characteristic at the swimmer's choice during the return stroke in order to utilize the increased resistance as a means of building swimmer's strength.